We all need breaks now and again to make it through the day. Chances are you've had days where you've needed ten breaks, and others where you've powered through without one. So, what's going on there, and what can you do about it? Time magazine has some answers.

The basics here are pretty simple:

That decision [to take a break] apparently hinges on a specific signal that at its peak—say, when your muscles are screaming that you can't do another rep or your brain refuses to focus on the page—prompts you to quit. And when your body and brain are refreshed and ready to go again, the signal quiets down and gets out of your way.

None of that should come as a surprise, as we've all likely had those moments where we simply couldn't concentrate any more. However, it turns out that that breaking point might not be set in stone:

The peaks and valleys that trigger these decisions, however, are not pre-set: they're influenced by how much effort you're expending and how big a reward you expect from the work. The bigger the reward and the smaller the effort required, the more likely you are to keep going until you've done what needs doing. As you work, it seems, your brain continuously calibrates your breaking point in relation to your expectations of gain.